Vaginosonographic velocimetry of both main uterine arteries by visual vessel recognition and pulsed Doppler method during pregnancy.

In 88 pregnant women (7 to 40 weeks' gestation) we performed Doppler velocimetric studies of the uterine artery on its course through the parametrium by means of the newly developed, frontally radiating duplex sector scanner. This device enabled us to visually recognize the vessel and apply the more refined pulsed wave system. In 71 of 88 women, we were able to obtain measurements from both uterine arteries. We found significant differences in the maximum systolic to minimum diastolic frequency shift (A/B ratio) up to 4 between the right and left vessels in the first and second trimester. In the third trimester, the differences almost disappeared (mean +/- SD A/B ratio difference 0.4 +/- 0.3) in these uncomplicated pregnancies. We also report our mean values (first, second, and third trimesters) of the A/B ratio and the pulsatility index as an average from the right and left side measurements. Both values declined during the course of pregnancy (A/B ratio, 5.5, 2.9, and 2.1; pulsatility index, 2.5, 1.7, and 1.3). We conclude that, with some experience, this scanner has the advantage of visually recognizing the vessel under study and allows measurements in both main uterine arteries. The average of the right and left measurements provides a better summary of uterine perfusion. Due to the significant right/left difference in the A/B ratio, unilateral measurements of the uterine artery may give erroneous results during the first and second trimesters. Theoretically, the pulsed system provides a "cleaner" signal, but the values are comparable to those of devices that apply a continuous wave system.